Integrated assessment of green hydrogen production in California: Life cycle Greenhouse gas Emissions, Techno-Economic Feasibility, and resource variability

This study explores green hydrogen production, focusing on life cycle assessment (LCA) and techno-economic feasibility; specifically, life cycle greenhouse gas emissions and hydrogen production cost. Existing literature lacks a comprehensive exploration of the impact of solar and wind resource variations, ambient conditions, and proton exchange membrane (PEM) electrolyzer sizing on the carbon intensity (CI) and hydrogen production cost. This work explores the relationship between the performance of photovoltaic (PV) and wind systems and the CI of renewable electricity in the U.S. Secondly, this study incorporates the hourly variations in solar and wind resources to assess the variation in hydrogen CI and production costs across California. The study examines how reductions in PEM and Renewable Energy Systems (RES) costs, technological advancements, and the inclusion of co-products' carbon dioxide equivalent (CO2eq) credits and revenues impact hydrogen CI and production costs. Wind-based systems consistently demonstrate lower CI (0.35 - 1.9 kg CO2eq/kg H2) except for the central regions (CI can reach up to 4.34 kg CO2eq/kg H2), with geographical variations larger than solar-based systems (1.58 2.95 kg CO2eq/kg H2). Similar trends are observed for the hydrogen production cost which varies between 1.5 and 15 USD/kg H2 for wind-based systems and between 3.0 and 5.2 USD/kg H2 for the PV-based systems. This study highlights the importance of optimal sizing of PEM electrolyzer to maximize its utilization for hydrogen production and the use of hourly-based models to assess the CI and production costs of hydrogen. Additionally, the geographical variation in the renewable energy resources and the ambient conditions are important factors that affect the hydrogen cost and the CI of both renewable electricity and green hydrogen.